Earthquake Source Parameters and Micro-tremor Site Characteristics Study-Geochemical Monitoring(III)

Earthquake Source Parameters and Micro-tremor Site Characteristics Study-Geochemical Monitoring(III)

Measurement of soil-gas emissions along active zones is demonstrated as geochemical tool to identify and monitor tectonic activity in the region. The present study is proposed to investigate geochemical variations of soil-gas composition in the vicinity of geologic fault zones of Hsincheng fault and the Hsinhua fault within the Hsinchu and Tainan areas, respectively, and to determine the influence of such formations on enhanced concentrations of different gases in soil to monitor the tectonic activity in the region. To carry out the present investigation variations in temporal soil-gases compositions was measured at continuous earthquake monitoring station established along Hsincheng and Hsinhua faults in Hsinchu and Tainan areas, respectively. Observations have shown potential precursory signals for some major earthquakes in the region. Results have shown that Hsinhua and Hsincheng faults have different tectonic settings. Hsinhua soil-gas variations show precursory signals for earthquakes occurring in south or south eastern part of Taiwan , whereas, for Hsincheng fault most of soil-gas variation precursory signals were recorded for the earthquakes that occurred along Okinawa Trough and Ryukyu Trough.